Human-machine interface has long been studied and different methods have been developed to interface with machines. Entering characters on a keyboard is one way of entering information into a machine. Using a mouse device is another method to enter information into a computer device by moving a cursor on a screen and pointing to a certain area to enter information. Further, a combination of a keyboard and a mouse device can be used to enter information into a computer device. However, instead of using a keyboard and a mouse combination, a touch panel can be used. A touch panel may either be placed over a display device or may be embedded on a display device or a mouse pad to enter information to a machine. Touch panels detect the object touching the surface of the touch panel and produces a signal that indicate the position of the touch. There are different touch technologies including resistive, capacitive, projected capacitive, acoustic, force and optical.
In recent years, the most popular technology is a projective capacitive technology due to its ability to detect multiple touches, meaning if several objects touch the touch panel at different locations, those touch locations of all the objects can be determined either simultaneously or in a very short period of time from each other.
Multiple touch projective capacitive touch panels detect the change in current or voltage due to change in capacitance when an object touches the touch panel. When a current is applied to an electrode of a capacitive touch panel all the capacitances on those electrodes are charged and this charging takes some time. This affects the speed of the panel.
Capacitive touch panels usually have electrodes placed on a substrate in two different directions that are substantially perpendicular to each other. For example electrodes on a horizontal axis are placed as multiple rows and electrodes on a vertical axis are placed as multiple columns. A typical structure is shown in FIG. 1. Electrodes can be either placed on a single layer or on two separate layers. When a single layer structure is used, electrodes are connected with conductive lines and the conductive lines of different axis are insulated from each other where they cross each other. Manufacturing process of a single layer touch panel, therefore requires adding insulator between the conductive lines of different directions.